Journal Article

Evidence for the presence of photorespiration in desiccation-sensitive leaves of the C<sub>4</sub> ‘resurrection’ plant <i>Sporobolus stapfianus</i> during dehydration stress

Tommaso Martinelli, Anne Whittaker, Celine Masclaux-Daubresse, Jill M. Farrant, Federico Brilli, Francesco Loreto and Concetta Vazzana

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 58, issue 14, pages 3929-3939
Published in print November 2007 | ISSN: 0022-0957
Published online November 2007 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/erm247

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The possible role of photorespiration as a general stress protection mechanism, and in C4 plant metabolism, is controversial. In particular, the potential involvement of photorespiration in the acquisition of desiccation tolerance in ‘resurrection’ plants is unknown. An investigation was carried out into whether photorespiration is present in leaves of the C4 resurrection plant Sporobolus stapfianus Gandoger (Poaceae) and whether it functions as a mechanism of stress resistance in the desiccation-tolerant younger leaves (YL) of this plant. It is shown that the enzymes involved in the photorespiratory pathway maintain their activity until 88% relative water content (RWC) in both YL and desiccation-sensitive older leaves (OL). In subsequent stages of dehydration stress, the enzymatic activity declined similarly in both YL and OL. The content of the phorespiratory metabolite, serine, and ethanolamine, a direct product of serine decarboxylation, is higher in the early stages of dehydration (88% RWC) in OL, suggesting a transiently enhanced photorespiratory activity in these leaves. This was confirmed by simultaneous gas exchange and fluorescence measurements, showing suppression of the electron transport rate in OL exposed to non-photorespiratory conditions (2% O2) at 85% RWC. It is concluded that a higher photorespiratory electron transport occurs in desiccation-sensitive OL, and it is therefore proposed that the capacity to scavenge excess electrons through photorespiration does not contribute to protect leaves of the desiccation-tolerant YL of S. stapfianus during the stress.

Keywords: Ethanolamine; glycine; photorespiratory enzymes; photosynthesis; poikilohydric plant; serine

Journal Article.  6703 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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